Objective: Early sexual maturation has been attributed to some environmental factors in recent years. Therefore, we aimed to evaluate the cases with premature thelarche. Methods: Among 1163 children attending the Child HealthCare Surveillance Unit between January 2006-December 2008, 15 cases identified clinically as premature thelarche had undergone a detailed examination and follow-up. The cases were compared to the control group for the nutrition of both mother and child and some domestic factors. Results: Fifteen (1,2 percent) cases were diagnosed as premature thelarche clinically. The mean age was 8.2 months (1-24 mos), and the mean age of diagnosis was 6.2 months. One case had increased FSH and another increased E2 levels. Cysts were identified in three cases on pelvic ultrasound examination. The mean time to the regression of the breast development was 5.4 months (4-8 months). One case was referred to with the diagnosis of early puberty. The normal delivery rate was higher among the cases. Although higher consumption of herbal tea was higher among the cases and fruit consumption was higher among the controls during pregnancy, no significant difference was found between the two groups for nutrition and environmental factors. Conclusion: The cases with premature thelarche should be closely followed-up as for early puberty. Concerns of the families should be resolved, and false practices such as cessation of breastfeeding should be prevented. Our study has some superiorities in that the infants and toddlers were followed up for a relatively long period, substantial information related to potential causes was collected, and our study population consisted of children younger than 2 years.